A volute type chemical slurry pump preparation method

Abstract

This invention provides a method for manufacturing a volute-type chemical slurry pump, comprising the following steps: integrally preparing an outer pump casing and an inner volute liner; cutting the inner volute liner to form a throat segment and several segments connected end-to-end; using the throat segment to be installed at the outlet hole of the outer pump casing as a reference, installing the first segment into the inner cavity of the outer pump casing from the inner hole of the stop joint, and then sequentially installing the remaining segments into the inner cavity of the outer pump casing from the inner hole of the stop joint, with the ends of adjacent segments connected; finally, installing the throat segment into the outlet hole, with the throat segment positioned between the first and last segments; inserting the outlet pipe from the outside of the outlet hole to the inside of the outlet hole, and matching the end of the outlet pipe with the throat segment; this invention has a compact structure and can significantly reduce the cost of use and maintenance.

Description

Technical Field

[0001] This invention relates to the field of chemical slurry pumps, and in particular to a method for preparing a volute-type chemical slurry pump. Background Technology

[0002] In the petrochemical industry, some refining processes require the transport of materials containing solid catalyst particles. Chemical process pumps made of conventional metal materials have a very short service life, necessitating the use of special high-hardness, wear-resistant metal materials. Because the petrochemical industry requires long-term, uninterrupted, and reliable operation, the technology described in patent application number 200610040604.4, which involves spraying a thin layer of wear-resistant alloy or ceramic material onto the surface of a pump casing made of conventional metal materials, is not adopted due to its short service life. A thicker wear-resistant lining is required to extend service life. However, high-hardness wear-resistant metals such as white cast iron are difficult to cast, brittle, and prone to cracking, shrinkage cavities, and leakage and damage risks, making them unsuitable as pressure-bearing materials for the flammable and explosive petrochemical industry. Therefore, a functional partitioned structure is needed, with a conventional metal material lining a wear-resistant inner shell, featuring an outer pressure-bearing and sealing layer and an inner layer for wear-resistant liquid flow channels.

[0003] Currently, two commonly used technologies are: For example, the slurry pump described in patent application number 201420059863.1 uses a conventional metal outer shell and front and rear pump covers for pressure sealing, and an inner shell made of wear-resistant material containing an integral internal flow channel to withstand erosion and wear. The disadvantage of this structure is that, because the entire inner volute shell needs to be installed inside the outer shell, the inner shell, due to its volute hydraulic flow channel, has a larger outer diameter. In addition, the connecting structure required for fixing the inner shell to the outer shell also increases the required inner diameter of the outer shell. According to the calculation formula for the pressure pump casing, the minimum wall thickness t is calculated as "t=(PA) / S" (Formula 1, where P is the internal pressure, A is the inner diameter of the pressure pump casing, and S is the allowable stress). The radial wall thickness is proportional to the diameter. Under the same pressure, the wall thickness of the outer shell is much larger than that of a conventional pump. Simultaneously, the weight of the outer shell side is m=π / 4. A2 t (Formula 2) is directly proportional to the square of the diameter and directly proportional to the wall thickness; substituting Formula 1 for the wall thickness t into Formula 2, we can obtain the weight calculation formula m = π / 4. A2 P A / S=π A3 / (4S), meaning the weight of the pump cover side is proportional to the cube of the diameter of the pressure-bearing housing's inner cavity. For the pump cover, the mating joint between it and the impeller, which was originally only required to install the impeller, needs to be increased to a size not less than the outer diameter of the inner housing containing the hydraulic flow channel volute. The increased pressure-bearing area results in an increase in pressure proportional to the square of the diameter. According to the formula for calculating the pressure-bearing end cover, the formula for calculating the minimum wall thickness t of the pump cover is "t=d". (Formula 3, where C is a coefficient and d is the diameter of the sealing surface with the pump body), which makes the wall thickness of the pump cover proportional to the diameter, significantly increasing it compared to the wall thickness of a conventional pump. Substituting Formula 3 into the calculation formula for a circular pump cover, its weight m = π / 4 d2 t=π / 4 d2 d =π / 4 d3 This means the weight of the pump cover is directly proportional to the cube of the increased diameter. Since the pressure exerted on the pump cover's bearing surface by the studs connecting the pump cover and the outer casing is proportional to the area of ​​the bearing surface, and this area is proportional to the diameter of the bearing surface, the bearing area of ​​the studs is directly proportional to the square of the diameter of the stop portion between the pump cover and the pump body. The increased diameter of the stop portion of the outer pump casing also necessitates an increase in the number or diameter of the studs connecting the pump cover and the outer casing to withstand the increased pressure. Therefore, these pumps are large and heavy, have high manufacturing costs, and require replacement of the entire inner casing after wear, resulting in high maintenance costs.

[0004] Another type, such as the lined slurry pump described in patent number 201610715531.8, solves the problem of excessively large outer pump casing diameter by splitting the integral inner liner casing into sections that are then assembled from the inner hole of a conventional pump casing stop. However, the inner liner casing manufactured by this technical solution is an integral structure covering the impeller periphery, resulting in significant material weight. Furthermore, in actual operation, the slurry pump often experiences the greatest wear in the high-solids-content area and the high-relative-velocity region between the impeller front cover plate and the inner wall of the inner liner casing, where the material is directly impacted at its maximum velocity. Once the inner liner casing fails due to localized wear, the entire inner liner casing needs to be replaced. However, the inner liner casing is made of a special hard alloy material, which is much more expensive than conventional materials, making maintenance and replacement costs still very high and resulting in poor economic efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing a volute-type chemical slurry pump that is compact in structure and can significantly reduce the cost of use and maintenance.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for preparing a volute-type chemical slurry pump, comprising the following steps: Step 1: Prepare the outer pump housing and inner volute as a whole; Step 2: Cut the inner liner shell to form a throat segment and several sub-segments that are connected end to end. Step 3: Using the throat section to be installed at the outlet hole of the outer pump housing as a reference, install the first segment into the inner cavity of the outer pump housing from the inner hole of the stop to fit the reference position. Then install the remaining segments into the inner cavity of the outer pump housing from the inner hole of the stop in sequence, with the ends of adjacent segments connected. Finally, install the throat section into the outlet hole, and position the throat section between the first segment and the last segment. Step 4: Insert the outlet tube from the outside of the outlet hole to the inside of the outlet hole, and match the end of the outlet tube with the throat section.

[0007] Furthermore, in step four, a positioning hole is provided circumferentially at the inner hole of the throat end, and a protruding ring is provided at the end of the outlet pipe. The protruding ring is inserted into the positioning hole to position the outlet pipe and the throat.

[0008] Furthermore, in step four, an annular groove is provided on the inner side of the outer end of the outlet hole along the circumference. After the outlet pipe is inserted into the inner side of the outlet hole, the retaining ring is embedded in the annular groove, and the side of the retaining ring abuts against the end of the outlet pipe.

[0009] Furthermore, in step two, when cutting the inner liner volute, adjacent segments are fitted with V-shaped grooves so that when several segments are sequentially installed into the inner cavity of the outer pump housing, the V-shaped grooves at the ends of adjacent segments fit together.

[0010] Furthermore, in step two, there is a first interface between the first segment and the throat segment, and a second interface between the last segment and the throat segment. The first interface and the second interface are set in parallel, and both the first interface and the second interface are perpendicular to the axis of the inner hole of the stop.

[0011] Furthermore, it also includes step five: installing the impeller into the outer pump housing from the inner hole of the stop and corresponding to the inner liner volute, installing the rear cover into the inner hole of the stop and sealing the inner hole of the stop, and the two ends of the impeller are rotatedly engaged with the outer pump housing and the rear cover respectively through sealing rings.

[0012] Furthermore, in step five, the outer wall of the impeller's front cover plate is curved, and the outer wall of the impeller's front cover plate and the inner wall of the outer pump casing are equidistant, with a spacing of 5-15mm.

[0013] Furthermore, the inner wall of the outer pump housing and the inner cavity are inclinedly transitioned, and the outer ring of the inner liner volute has inclined guide surfaces on both sides, so that the guide surfaces and the inner cavity are guidedly engaged when the inner liner volute is installed.

[0014] Furthermore, the width of the inner volute is 10-30mm wider than the width of the outer ring of the impeller, and the diameter of the inner hole of the stop is 1-10mm larger than the diameter of the impeller.

[0015] Furthermore, the inner liner casing is made of a wear-resistant material.

[0016] The beneficial effects of this invention are as follows: Because the width of the inner volute in this design is 10-30mm wider than the outer ring of the impeller, both the solid-liquid two-phase materials ejected from the flow channel between the impeller blades and the solid materials separated by the circulation formed by the friction of the discs on both ends of the impeller cover plate can be protected from direct impact by the inner volute. Setting the distance between the impeller front cover plate and the inner wall of the outer pump casing to 5-15mm, and making the inner wall of the outer pump casing and the inner cavity inclined, reduces lateral circulation losses while ensuring the width of the inner volute is not excessive. The distance between the outer diameter side of the impeller and the impeller inlet sealing ring remains constant, resulting in a larger space in the inner cavity compared to conventional designs. This makes it easier for internal circulation to occur, causing solid particles to easily accumulate at corners due to centrifugal separation, exacerbating local wear. The same-spaced cavity design in this design allows the centrifugal force generated by the circulation during operation to directly throw solid particles into the inner volute in the outer diameter direction, where they are carried away by the mainstream, significantly reducing wear on the inner wall of the pump casing. Therefore, in this solution, the inner wall of the outer pump casing can be used as part of the outer pump casing and can be directly manufactured using conventional metal materials, which simplifies the structure and reduces manufacturing costs and subsequent maintenance and replacement costs.

[0017] The inner volute adopts the spiral pressure chamber design of a centrifugal pump, which conforms to hydraulic principles and ensures hydraulic efficiency. The inner volute, made of wear-resistant special alloy material, has a rectangular cross-section with an inclined guide surface and only a spiral rim. Compared with the fully enclosed inner volute of the slurry pump with patent number 201610715531.8, the weight is significantly reduced, the manufacturing cost and the user's maintenance and replacement cost are greatly reduced, and the efficiency of equipment use is improved.

[0018] The inner liner volute is cut using wire cutting or laser cutting, resulting in small gaps and negligible changes in its shape after assembly, thus not affecting hydraulic performance. The V-groove cutting and fitting method allows the assembled sections of the inner liner volute to interlock seamlessly, preventing displacement or detachment without additional structural support. Furthermore, the first and second interfaces on both sides of the throat are cut along parallel lines, allowing the throat to be horizontally inserted into the remaining space of the inner liner volute after the other sections are assembled. The throat is positioned using the insertion end of the outlet pipe through the positioning hole, preventing it from falling off in the reverse direction of insertion. The upper end of the outlet pipe is held in place by a retaining ring to prevent it from detaching towards the outlet. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention.

[0020] Figure 2 This is a schematic diagram of the assembly of the outlet pipe in this invention.

[0021] Figure 3 This is a force analysis diagram of the fluid in this invention.

[0022] Figure 4 This is a schematic diagram of the assembly of the throat segment and the sub-segments in this invention.

[0023] Figure 5 This is a schematic diagram of the guiding surface in this invention.

[0024] Figure 6 This is a schematic diagram of the structure of a conventional chemical slurry pump. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0027] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0028] like Figures 1-6 The present invention provides a method for preparing a volute-type chemical slurry pump, comprising the following steps: Step 1: Prepare the outer pump housing 1 and the inner volute housing 2 as a whole; The inner liner volute 2 is made of wear-resistant materials, such as high-chromium white cast iron or nickel-based wear-resistant cast alloy.

[0029] Step 2: Cut the inner liner volute 2 so that the inner liner volute 2 forms a throat segment 3 connected end to end and several segments 4. When the inner liner volute 2 is cut, adjacent segments 4 are fitted with V-shaped grooves 12 so that when several segments 4 are installed sequentially into the inner cavity 19 of the outer pump housing 1, the V-shaped grooves 12 at the ends of adjacent segments 4 are interlocked; the first segment 4 and the throat segment 3 have a first interface 13, and the last segment 4 and the throat segment 3 have a second interface 14. The first interface 13 and the second interface 14 are set in parallel, and both the first interface 13 and the second interface 14 are perpendicular to the axis of the stop hole 6.

[0030] Step 3: Using the throat section 3 to be installed at the outlet hole 5 of the outer pump housing 1 as a reference, install the first segment 4 into the inner cavity 19 of the outer pump housing 1 from the inner hole 6 of the stop, and then install the remaining segments 4 into the inner cavity 19 of the outer pump housing 1 from the inner hole 6 of the stop in sequence. The ends of adjacent segments 4 are connected. Finally, install the throat section 3 into the outlet hole 5, and make the throat section 3 located between the first segment 4 and the last segment 4. Step 4: Insert the outlet tube 7 from the outside of the outlet hole 5 to the inside of the outlet hole 5, and match the end of the outlet tube 7 with the throat section 3.

[0031] The throat section 3 has a positioning hole 8 circumferentially opened at the inner hole of the end, and the outlet pipe 7 has a protruding ring 9 at the end. The protruding ring 9 is inserted into the positioning hole 8 to position the outlet pipe 7 with the throat section 3. The outer end of the outlet hole 5 has an annular groove 10 circumferentially opened on the inner side. After the outlet pipe 7 is inserted into the inner side of the outlet hole 5, the retaining ring 11 is inserted into the annular groove 10, and the side of the retaining ring 11 abuts against the end of the outlet pipe 7.

[0032] Step 5: Install the impeller 15 into the outer pump housing 1 through the inner hole 6 of the stop and align it with the inner liner volute 2. Install the rear cover 16 into the inner hole 6 of the stop and seal the inner hole 6. The two ends of the impeller 15 are rotatedly engaged with the outer pump housing 1 and the rear cover 16 respectively through the sealing rings 17.

[0033] The outer wall of the front cover plate 18 of the impeller 15 is curved, and the outer wall of the front cover plate 18 of the impeller 15 and the inner wall of the outer pump casing 1 are equidistant, with a spacing of 5-15mm; and a bearing box is connected to one end of the impeller to control its rotation.

[0034] Preferably, the inner wall of the outer pump housing 1 and the inner cavity 19 are inclinedly transitioned, and the outer ring of the inner liner volute 2 has inclined guide surfaces 20 on both sides, so that when the inner liner volute 2 is installed, the guide surfaces 20 and the inner cavity 19 are guided to fit together, so that the segmented and throat structures of the inner liner volute can be guided into the inner cavity through the guide surfaces and maintain a stable and accurate installation posture.

[0035] In one embodiment of this solution, the width of the inner liner volute 2 is 10-30 mm wider than the width of the outer ring of the impeller 15, and the diameter of the stop hole 6 is 1-10 mm larger than the diameter of the impeller 15.

[0036] It is worth mentioning that during operation, the impeller, through centrifugal force generated by its rotation, propels the solid-liquid two-phase medium between the impeller blades out along the blade channel. According to hydraulic design theory, at the blade outlet, the medium flows out along the blade's inclined direction at a relative velocity Vx. The impeller's high-speed rotation generates a circumferential velocity U, and the medium's actual absolute velocity is the sum of these two velocities, V. In other words, the solid-liquid two-phase medium being transported is forcibly thrown out by the impeller, and its velocity relative to the stationary inner liner volute is V. Flow field analysis shows that high-density solid particles, due to greater centrifugal force, have a larger angle between their actual direction of motion and the direction of rotation. This is similar to a stone directly hitting the ground, causing the most severe wear on the inner wall of the volute at the impeller outlet. As for the sides of the flow channel, as long as there are no areas directly impacted by the fluid and no solid particles accumulate, the direction of fluid rotation is basically consistent with the wall shape, similar to the movement of the medium within a transport pipeline. Therefore, wear is relatively minor. Even using conventional metal materials, as long as the necessary wall thickness margin is maintained according to standards, no maintenance or replacement is required during the pump's normal lifespan. Therefore, this technical solution adopts the method of setting wear-resistant inner liner volute only in the part along the impeller outlet direction (i.e., the inner cavity position), which not only ensures the wear resistance life of the pump casing, but also significantly reduces the cost of maintenance and replacement of the inner liner volute.

[0037] To further illustrate the preparation process of the chemical slurry pump in this solution, the following detailed description is provided in conjunction with specific embodiments: 1. When designing the hydraulic system for the inner volute liner, the width of the inner volute liner should be 20mm larger than the width of the outer ring of the impeller. 2. Set the distance between the impeller front cover plate and the inner wall end face of the outer pump casing to 10mm, and keep the space distance from the outer diameter side of the impeller to the impeller inlet sealing ring constant. 3. Design the profile of the volute-shaped volute chamber on the inner wall of the volute casing according to the hydraulic design requirements of the centrifugal pump volute chamber, and set the radial wall thickness according to the expected wear life of the material used. 4. The outer pump casing is arranged close to the outer wall and end face of the inner liner volute, and the wall thickness of the outer pump casing is determined by design calculation according to the design pressure requirements; 5. Determine the inner diameter of the stop hole of the outer pump casing by adding 5mm to the outer diameter of the designed impeller; 6. The inner liner volute, including the segments and throat section, is integrally cast using wear-resistant materials, while the outer pump casing is integrally cast. 7. The outer pump casing is machined as a whole, including the contact end face between the inner wall and the inner liner volute and the inner wall surface, as well as the inner hole for installing the outlet pipe. The outlet pipe is also machined from steel pipe or bar stock. 8. Machining the end face and outer wall surface of the inner liner volute, including the positioning hole for alignment with the convex ring of the outlet pipe; 9. Design the inner liner volute according to the requirements of the inner hole of the outer pump housing stop, and ensure that the longest inner liner volute after segmentation can be inserted into the inner cavity of the outer pump housing from the inner hole of the stop. The first and second interfaces on both sides of the throat section near the outlet hole are designed in parallel, and the remaining segments are designed with concave and convex V-shaped groove cutting surfaces. 10. Cut the inner liner casing according to the aforementioned design using wire cutting or laser cutting; 11. Using the scribing method, with the outlet hole as the reference, scribing out the assembly reference surface of the throat section near the outlet hole. Then, the first inner liner volute of the assembly reference surface is segmented and enters the inner cavity through the stop hole of the outer pump housing. The end is aligned with the assembly reference surface and snapped into the inner cavity of the outer pump housing, resting against the inner wall surface of the outer pump housing. 12. Install the adjacent inner liner volute sections in sequence according to the above method, and use the V-grooves at both ends to lock them in place to prevent them from falling off; 13. Finally, insert the throat section into the remaining empty part of the inner liner volute, insert the outlet pipe from the outlet hole of the outer pump housing into the throat section positioning hole, and use a retaining ring to position it to prevent it from falling off.

[0038] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method of manufacturing a volute chemical pulp pump, characterized in that Includes the following steps: Step 1: Prepare the outer pump housing (1) and the inner volute housing (2) as a whole; Step 2: Cut the inner liner volute (2) to form a throat segment (3) and several segments (4) that are connected end to end. Step 3: Using the throat section (3) to be installed at the outlet hole (5) of the outer pump housing (1) as a reference, install the first segment (4) into the inner cavity (19) of the outer pump housing (1) from the inner hole (6) of the stop, and then install the remaining segments (4) into the inner cavity (19) of the outer pump housing (1) from the inner hole (6) of the stop in sequence. The ends of adjacent segments (4) are connected. Finally, install the throat section (3) into the outlet hole (5) and make the throat section (3) between the first segment (4) and the last segment (4). Step 4: Insert the outlet tube (7) from the outside of the outlet hole (5) to the inside of the outlet hole (5), and match the end of the outlet tube (7) with the throat section (3).

2. The manufacturing method of volute chemical pulp pump according to claim 1, characterized in that: In step four, a positioning hole (8) is provided circumferentially at the inner hole of the throat section (3), and a protruding ring (9) is provided at the end of the outlet pipe (7). The protruding ring (9) is embedded in the positioning hole (8) to position the outlet pipe (7) with the throat section (3).

3. The manufacturing method of volute chemical slurry pump according to claim 1, characterized in that: In step four, an annular groove (10) is provided on the inner side of the outer end of the outlet hole (5) along the circumferential direction. After the outlet pipe (7) is inserted into the inner side of the outlet hole (5), the retaining ring (11) is embedded in the annular groove (10), and the side of the retaining ring (11) abuts against the end of the outlet pipe (7).

4. The manufacturing method of volute chemical slurry pump according to claim 1, characterized in that: In step two, when the inner liner volute (2) is cut, the adjacent segments (4) are fitted with V-shaped grooves (12) so that when several segments (4) are installed in sequence into the inner cavity (19) of the outer pump housing (1), the V-shaped grooves (12) at the ends of the adjacent segments (4) are interlocked.

5. The manufacturing method of volute chemical slurry pump according to claim 1, characterized in that: In step two, there is a first interface (13) between the first segment (4) and the throat segment (3), and a second interface (14) between the last segment (4) and the throat segment (3). The first interface (13) and the second interface (14) are set in parallel, and both the first interface (13) and the second interface (14) are perpendicular to the axis of the inner hole (6) of the stop.

6. The manufacturing method of volute chemical pulp pump according to claim 1, characterized in that: The process also includes step five: installing the impeller (15) into the outer pump housing (1) through the inner hole (6) of the stop and corresponding to the inner liner volute (2); installing the rear cover (16) into the inner hole (6) of the stop and sealing the inner hole (6); and having the two ends of the impeller (15) rotate with the outer pump housing (1) and the rear cover (16) respectively through the sealing ring (17).

7. The volute chemical pulp pump manufacturing method of claim 6, wherein: In step five, the outer wall of the front cover plate (18) of the impeller (15) is curved, and the outer wall of the front cover plate (18) of the impeller (15) and the inner wall of the outer pump casing (1) are equidistant, with a spacing of 5-15mm.

8. The manufacturing method of volute chemical pulp pump according to claim 1, characterized in that: The inner wall of the outer pump housing (1) and the inner cavity (19) are inclined to transition, and the outer ring of the inner liner volute (2) has inclined guide surfaces (20) on both sides, so that the guide surfaces (20) and the inner cavity (19) are in a guiding fit when the inner liner volute (2) is installed.

9. The manufacturing method of volute chemical pulp pump according to claim 6, characterized in that: The width of the inner volute (2) is 10-30 mm greater than the width of the outer ring of the impeller (15), and the diameter of the inner hole (6) of the stop is 1-10 mm greater than the diameter of the impeller (15).

10. The method of claim 1, wherein the method further comprises: providing a volute; and providing a pump housing having a cylindrical portion and a volute portion. The inner liner (2) is made of wear-resistant material.

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